A game unit comprises a CPU, one or more memories, output/input (I/O) interfaces and an image processing unit.
The image processing unit comprises a VRAM (Video Random Access Memory), a VDC (Video Displaying Controller) and a VDE (Video Displaying color Encoder). The game unit is connected with a home TV by using the I/O interface. The VDE has a color pallet table which relates to a color code for outputting an image data and a color code for a game program.
In the game unit, the image data is processed and then outputted to the home TV through the I/O interface. The processed image data is displayed on the home TV by using scanning lines. It takes 1/60 second to display one image by the scanning lines (namely, an image displaying cycle is 1/60 second). Therefore, a neat image must be prepared within 1/60 second.
In a conventional method for programming a TV-game, when the next image is not prepared in the VRAM within a predetermined time such as the image displaying cycle, a programmer modifies a TV-game program. Further, if a next image processed by the modified TV-game program us not prepared in the VRAM within the predetermined time, a programmer must cut off one or more steps of the TV-game program.
In the conventional method for programming a TV-game, however, there are disadvantages in that a TV-game becomes very simple and rough, because the steps of the TV-game program are cut off.